Tire loading apparatus has been employed in conjunction with tire curing presses for many years. Originally, tire loading apparatus was developed for purposes of automation to relieve the labor-intensive operations which had, for many years, characterized the production of pneumatic tires. Early tire loading apparatus employed in conjunction with tire curing presses did not place emphasis on positioning accuracy of the tire baskets of tire loading apparatus, as such was not deemed to be of particular importance, and center mechanisms were designed to carry out alignment functions to the extent such was deemed to be of importance by tire manufacturers. Variations in tire loading apparatus were primarily made to accommodate particular types of tire curing press center mechanisms and to accommodate particular tire configurations that evolved.
Since the virtual universal acceptance of radial-ply tires, tire manufacturers have adopted the philosophy that accurate location of an uncured tire at the center of the lower mold cavity of a tire curing press is essential to the production of a high-quality radial tire. It has thus become common for tire manufacturers to require repeat loading accuracy of uncured tires to precision on the order of thousandths of an inch. The precise positioning of an uncured tire with respect to the center of the lower mold cavity of a tire curing press involves two primary considerations.
First, the tire loader itself, which consists of a movable arm or other member, must be capable of repeat precision movement between two positions that are horizontally spaced. In this respect, it is necessary to bring the loader basket from a position where its centerline is aligned with a fire stand, tire holder, or conveyor position having an uncured tire located thereon, for picking up the uncured tire, and to transport it to a position in precise alignment with the lower mold cavity of a tire curing press or other apparatus into which the uncured tire is to be deposited. Numerous loaders having various arrangements of pivoting arms are known in the art to provide arcuate movement of a tire loader basket between two fixed positions. The present invention contemplates the utilization of such a loader arm or other member capable of moving a tire loader basket between two spaced positions.
The second facet of precision loading involves the precise positioning and movement of the shoes or tire-engaging members of the tire loader basket relative to the central axis of the loader basket. This requires that the loader shoes be radially independently adjustable relative to the central axis of the loader basket. Ancillary to this requirement is the necessity that the shoes of the loader basket remain in precise concentricity with the center axis of the loader basket over the entire range of radial adjustment of the shoes of the loader basket to accommodate a range of bead sizes for the different tire sizes that a fire curing press is constructed to accommodate for flexibility and economy of production. Thus, besides the necessity that the shoes of a tire loader basket move radially inwardly and outwardly to disengage and engage the upper bead of an uncured tire, it is additionally necessary that all of the shoes be capable of concentric radial adjustment to different stop positions to service the different tire bead sizes for which a particular tire loader basket is designed.
Prior-art tire loader baskets have been variously constructed to perform the functions of engaging and releasing an uncured tire and for radial adjustment to appropriately engage and disengage uncured tires having differing bead diameters. In some cases, oscillating actuating plates having a cam or scroll plate have been employed to actuate all shoes of a tire loader basket simultaneously. In other instances, individual cylinder actuators have been employed for each loader shoe of a loader basket. Various types of stops and adjustable rods have been employed for purposes of establishing the radially inner and/or outer position of the shoes of a loader basket for each different tire bead size. The lack of initial setting precision, the lost motion in employing a plurality of interconnected components, the large bead range requirements, necessitating awkward and time-consuming shoe range adjustments, and the tendency of some types of components to develop premature wear characteristics, all of which affect accuracy and cost, have precluded a broad-based adoption of any single tire loader basket design.